For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
Phone: 978-250-3343 Fax: 978-250-3373 Order On-line at www.hittite.com
Application Support: Phone: 978-250-3343 or apps@hittite.com
DATA CONVERTERS - SMT
11
HMCAD5831LP9BE
v03.0818
3-BIT 26 GSPS ANALOG-TO-DIGITAL
CONVERTER W/ OVERRANGE, INHIBIT, AND 1:2 DEMUX
Operation Over Full Temperature Range
Application Information (continued)
The device typically consumes 4.2 watts power and thus requires careful thermal design at the system level. A heat
sink of at least 25 cm^2 surface area is required under all conditions. Most of the device heat dissipation occurs on
the bottom side of the package. The package has a thermal paddle on the bottom side. The PCB design must solder
this paddle through a grid of several thermal vias to a metal pad on the bottom side of the PCB where the heat sink
should be attached. In addition, the AVEE pins of the device and the paddle must be connected to the negative
-5V supply plane. It is highly recommended that some manner of additional cooling technique should be employed in
order to maximize the ambient temperature range of the device’s operation.
The Electrical Specications section lists only the performance parameters at +25 °C temperature. The performance
diminishes as temperature increases. On the device evaluation board, in Hittite lab settings with minimal air ow, a
temperature rise of 18-20 °C was observed between the ambient temperature and the thermal pad at the bottom of
the PCB. The ultimate limit to the device’s temperature capabilities is the maximum junction temperature specied in
the Absolute Maximum Ratings table in this document. The thermal resistance from the device junction to the device
thermal paddle is specied in the Thermal Information table. With this information and knowledge of the system’s
heat dissipation capabilities from the PCB pad to the ambient, one can determine the ambient temperature range the
device can support.
Based on data taken on the device evaluation board under Hittite’s lab conditions, it is believed that 22 GS/s maximum
speed can be expected across the temperature range of -40 °C and +85 °C with reasonable system thermal design.
Typical Operation Example
When using the device evaluation board, high-quality signal generator equipment must be used that provides low
enough broadband phase noise to support the SNR specications of this device at the very high signal frequencies.
The reference ladder voltages should be provided with stable, linear power supplies. As a starting point, it is
recommended that the RTF and RBF voltage should be set to -772 mV and -1.028V, as described in the Reference
Ladder subsection. The input signal can then be provided with the appropriate signal generator with 50 Ohm, single-
ended output that is ac-coupled into the eval board’s SMA connector. The signal generator output strength should be
set at a low level such as -20 dBm before the output is enabled. The signal level can then be increased gradually as
required, but never beyond the 256 mV full-scale swing that had been selected in this example. The Clock input can
similarly be provided with an RF signal generator or a Hittite PLL/VCO device evaluation board, provided that the CKN
input is set at the common-mode point – 0 V (AGND) in this case. Although higher amplitudes are possible, initially
the user should keep the clock signal strength at -3 dBm or less. And, of course, care should be taken with the clock
input as well to not overload the ADC.
An FPGA with suitably fast SERDES inputs can capture data from the HMCAD5831LP9BE using the following routine.
The FPGA produces an INHIBIT high signal causing the ADC core to produce all 0s. The XOR input to the ADC runs
at a slow clock rate and modulates the ADC output to produce a known waveform at the FPGA inputs. The FPGA then
uses these signals to align the lanes. When the lanes are aligned, the INHIBIT signal goes low and the ADC produces
signal data that continues to be modulated by the XOR input. The FPGA then corrects for the modulation. Note that
the FPGA can generate the XOR modulation signal (in which case a PRBS sequence could be used). Depending on
the phase of the XOR input modulation waveform, either demux output (X or Y) can be the leading data sample. In this
case, the FPGA would need to resolve which lane is the leader. This can be accomplished by driving the ADC with a
known signal, evaluating the outputs and reassembling FPGA data if necessary. It is recommended to do this on each
power-up. It is also recommended to perform a routine to ensure that the XOR input waveform is properly aligned with
the internal clock. This can be accomplished by sweeping the external variable delay stage.
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
For price, delivery, and to place orders: Analog Devices, Inc.,
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106
Phone: 781-329-4700 • Order online at www.analog.com
Application Support: Phone: 1-800-ANALOG-D